   that tests if `2 * 2 = 4`. Remember to update `tests-to-run`. You can use the `ns` preamble from `sample-spec` to
   get the various requires correct.
 
+  Solutions are in `exercises-solutions-spec`.
+
   ## Assertions
 
   Special arrows:


  Create an additonal spec (in the same file as before) that uses the `=fn=>` arrow to check that an expression results
  in an even value.

  ## Mocking


  but *really* allows the original `sum-sq` to generate the real value. Add assertions that talk about how every result
  is positive, even when the pairs contain negatives. The macro `provided` is the same as `when-mocking`, but allows you
  to add a string to the output (and nest the outline a level deeper) to describe what the mocking is proving.

  Solutions are in `exercises-solutions-spec`.

  ## Timeline testing

